Effect of immobilization and cold stress on sympatho-adrenal system in rats exposed to long-term cold

Abstract

In the present study we examined changes in plasma levels of catecholamines, corticosterone and adrenomedullary TH gene expression after a short (2 h) and long-term (28 days) cold exposure, as well as in the cold adapted rats exposed to immobilization. Long-term cold produced a significant elevation of basal plasma levels of noradrenaline, but not of adrenaline, corticosterone and adrenal TH mRNA. Cold-adapted rats exposed to immobilization further significantly elevated plasma levels of catecholamines, corticosterone and adrenal TH mRNA, in comparison with repeated short (2 h) exposure to cold. The response of these animals was more pronounced in comparison with naive rats exposed to the same stressor at room temperature. Based on the results obtained it can be concluded that the rats exposed to long-term cold are able to respond to another stressor by a higher activation of the sympatho-adrenal system as compared to the rats kept at room temperature.